What Are the Causes and Effects of Brain Stem Injuries?
September 15, 2022 | Sagi Shaked
Brain injuries are one of the most catastrophic injuries you can suffer. Depending on the region injured and the severity of the injury, a brain injury can produce physical, cognitive, and emotional symptoms.
The brain stem controls many of your body’s involuntary – or autonomic – functions. Some of these functions, like heart rate and respiration, must continue, or you will die. Brain death, a condition from which you cannot recover and require artificial means to stay alive, happens when your brain stem suffers permanent damage.
Here’s an overview of the causes and effects of a brain stem injury.
What Is the Anatomy of Your Brain?
Your brain controls your entire body. The brain consists of neurons that communicate with each other through chemical and electrical signals. These neurons form thoughts and store information by creating connections between neurons. The stronger the connection, the better the brain understands the skill or information stored there.
The brain receives information from your sense organs and decides how to control your body. Some of the sensory responses require conscious thought. You make a conscious decision to raise your hand to catch a ball that you see flying toward you.
But other brain functions do not require conscious thought. Your sweat glands perspire automatically when your brain senses an increase in body temperature. Your brain still triggers this response, but it does not require you to make a conscious decision.
Autonomic responses include:
- Blood pressure
- Temperature regulation
- Sexual arousal
Some body functions involve both autonomic responses and conscious decisions. For example, you exert conscious control over emptying your bowel or bladder. But when you cannot control them, such as when you are unconscious, your brain will automatically empty them for you.
Different areas of your brain control different brain functions. Your brain stem sits at the base of your brain, just above your spinal cord. It is sometimes called your animal brain because it does not control any higher brain functions. Instead, it controls the most primitive brain functions, such as autonomic functions.
Causes of Brain Stem Injuries
Because of its location, brain stem injuries happen infrequently. The skull and spine protect the brain stem from the jolts that can cause a concussion or even a contusion. This leaves only a few ways your brain stem can sustain an injury.
Lack of Oxygen
Your brain cells require oxygen for cell metabolism. Brain cells die after about four minutes without oxygen.
Your circulatory system delivers oxygen to your brain cells through the blood. Blood gets oxygenated in your lungs, and the heart pumps it to the brain. The blood cells drop off oxygen in your brain and pick up carbon dioxide.
Your brain stem can experience a lack of oxygen – or anoxic injuries – in a few ways. Severe bleeding can cause massive blood loss and a drop in blood pressure. Together, these effects can deprive your brain of oxygen.
Drowning or suffocation can also cause anoxic injuries. If you cannot breathe, your lungs cannot supply oxygen to your blood cells. Your brain cells die from a lack of oxygen.
Pressure in your brain can squeeze the blood vessels in your brain. Blood cannot flow through the compressed blood vessels, depriving your brain of oxygen. For example, if you rupture a blood vessel in your brain during a pedestrian accident, the blood pumping into your skull can squeeze your brain.
Blood clots can also block blood flow in your brain. If a blood clot forms in your brain or travels to your brain from elsewhere in your circulatory system, the area of your brain connected to the blocked blood vessel will die.
Penetrating injuries happen when an object enters your skull and damages the brain stem.
If an object falls onto you and pierces your skull in a workplace accident, you could suffer a brain stem injury. Similarly, if you slip and fall onto a sharp object, the object could damage your brain stem.
Diffuse Axonal Injury
Your brain includes long neurons called axons. When your brain gets shaken, these axons can tear, producing a diffuse axonal injury (DAI). Doctors also refer to DAIs as “shaken baby syndrome.” DAIs are serious, often fatal, brain injuries.
Effects of Brain Stem Injuries
Brain stem injuries affect your autonomic functions. The brain stem includes three regions. Each of these regions handles a different set of functions.
The midbrain consists of the top portion of the brain stem. It controls eye movement, hearing, sleep, wakefulness, and temperature regulation.
The pons sits in the middle of the brain stem. It is the junction for the cranial nerves that collect sensory information from your eyes, ears, nose, and tongue and send control signals to your facial muscles. It also manages pain signals, motor signals, balance, and wakefulness.
The medulla oblongata rests at the base of the brain stem. It controls your vital autonomic signals, including your breathing, heartbeat, and blood pressure.
Some of the effects of brain stem injuries include:
If a brain stem injury affects the medulla oblongata, you could stop breathing, or your heart could stop beating.
A coma happens when you suffer a prolonged period of unconsciousness. Since the brain stem controls sleep and wakefulness, damage to the brain stem can cause a coma.
Locked-in syndrome is a form of paralysis. But since your brain stem runs to both your cranial nerves and your spinal cord, you experience total paralysis. Unlike quadriplegia, this paralysis includes everything above and below your neck.
The tragedy of locked-in syndrome is that the rest of the brain continues functioning. This means you retain your intelligence and memories. But you have no way of communicating, and you have no control over anything outside your brain.
You could experience a less severe form of paralysis than locked-in syndrome after a brain stem injury. Many of your motor controls pass through your brain stem. Disruption of these controls can paralyze you above or below your neck.
Recovering from a Brain Stem Injury
The brain does not grow new neurons. It also cannot repair brain damage. But it can remap functions lost to healthy parts of the brain.
In some cases, intense therapy after a brain stem injury can help you recover some of your lost faculties. But this therapy is often costly, and your injuries will likely prevent you from working.